Microgram to Milligram Converter
Convert micrograms (µg) to milligrams (mg) and back. 1 milligram = exactly 1,000 micrograms.
Reviewed October 7, 2026 Runs in your browser — inputs are never stored
1 Micrograms (µg) = 0.001000 Milligrams (mg)
Milligrams = Micrograms ÷ 1000
This tool provides general unit conversions for everyday and educational use. For regulated, legal, or scientific applications, verify conversion factors against the applicable official standard.
About the Microgram to Milligram Converter
The microgram to milligram converter uses the exact relationship 1 mg = 1,000 µg. Vitamins such as B12, D and folic acid and some medicines are dosed in micrograms, and confusing µg with mg means a thousandfold error. This tool makes the conversion explicit in both directions. Always follow the dose on the label or from your pharmacist.
How to use it
- 1Enter the amount in micrograms.
- 2The equivalent in milligrams appears instantly.
- 3Press the ⇌ button to convert from milligrams back to micrograms.
- 4Choose how many decimal places to show if you need more or less precision.
Worked example
400 µg of folic acid ÷ 1,000 = 0.4 mg, and 2.5 mg × 1,000 = 2,500 µg.
How it works
Formula
mg = µg ÷ 1000
µg = mg × 1000
Medical applications
Micrograms are critical in pharmaceutical dosing — many supplements (B12, folic acid, vitamins D and K) are measured in micrograms. 1 µg = 1 microgram = 10⁻⁶ grams.
Conversion table
| µg | mg |
|---|---|
| 1 | 0.001 |
| 10 | 0.01 |
| 100 | 0.1 |
| 500 | 0.5 |
| 1000 | 1 |
| 2500 | 2.5 |
| 5000 | 5 |
Common use cases
- Comparing supplement labels that use different units
- Checking dosage units on prescriptions
- Lab and science calculations
Frequently asked questions
A:Very potent drugs have therapeutic doses in the microgram range — even tiny differences matter. Using µg avoids decimal errors (e.g., writing 0.1 mg risks a 10× overdose; writing 100 µg is safer).
A:1 g = 1,000 mg = 1,000,000 µg. The prefix micro- means 10⁻⁶.
Reviewed for accuracy · Last updated October 7, 2026
Conversion factors are based on internationally defined SI units and standard metric/imperial equivalence tables.
CalcWisee Editorial Team
Calculator development and formula review
CalcWisee is an independent site founded by Ayman. Every calculator is built from a published formula or official definition, tested against hand-worked examples before it goes live, and corrected promptly when a reader reports an issue to ayman@calcwisee.com.
Expertise: Financial mathematics, Health and fitness formulas, Applied mathematics, Unit conversion standards
References & sources
Related guides
Common Unit Conversion Formulas Made Simple
Length, weight, temperature, and volume conversions explained with exact factors, worked examples, and common mistakes to avoid.
Length Converter: Convert Units Accurately
Convert any length or distance unit accurately — from kilometres and metres to miles, feet, and inches — with practical conversion tables, formulas, and real-world examples.
Temperature Converter: Celsius, Fahrenheit & Kelvin
Convert Celsius, Fahrenheit, and Kelvin with exact formulas — plus tables, absolute zero, the −40 crossover, and practical examples for weather, cooking, and science.